Twenty minutes into his regular weekly bicycle ride through the side streets of Brooklyn, Sen. Charles Schumer pauses and jerks his finger toward an elderly Hasidic Jew intently studying his high-tech cellphone.

“Is this a great country or what,” he says of the cultural contrast, quickly turning back toward the street ahead and narrowly avoiding a crash with a woman pushing a stroller between two parked cars.

So it goes for New York’s unassuming but famously hardworking senior senator, who loves to take long weekend rides so he can get a little exercise, reacquaint himself with New York’s boroughs and check in on constituents when he’s not in Washington.

Although Schumer’s rides are often unplanned, The Post accompanied him on a recent Sunday afternoon trip, spanning almost a dozen miles through some of Brooklyn’s oldest neighborhoods.

Beginning at his home near Prospect Park, Schumer rolled his bike – a Bianchi – out past his doorman and into the winter chill.

We pedaled past the Brooklyn Public Library and the Brooklyn Botanic Garden before pushing into Crown Heights. He sticks to bike paths when he can, noting the conflicts he’s had with wife Iris Weinshall, the city’s transportation boss, who does not place the same importance on creating these paths as he does: “The bike people drive her crazy, but they know they have an ally in me,” Schumer says.

The highlight of the ride is usually a stop at some bakery or deli where he can grab something to eat. On this day, we drop by San Marco Pizzeria where he chats with customers who comment on the neighborhood or the Jets or the health of various friends and family before we head back into the cold.